Glossary
- R's

Radial
clearance (r) the difference in the radial dimensions between
the sealing surfaces of a radial seal.

Radicals
atoms or polyatomic molecules with at least one unpaired electron.

RCA
Clean (sc) a multi-step wet chemical process to clean wafers
before oxidation; named after RCA, the company that invented the procedure.

Reactive
ion etching (RIE) (sc) an etching process that combines plasma
and ion beam removal of the surface layer. The etchant gas enters
the reaction chamber and is ionized. The individual molecules accelerate
to the wafer surface. At the surface, the top layer removal is achieved
by the physical and chemical removal of the material.

Recipe
(r) a formula, mixing procedure and any other instructions needed
for the preparation of a product.

Recovery
(r) the degree to which a rubber product returns to its normal dimensions
after being distorted.

Reinforcement
(r) the act of increasing the mechanical performance capability
of a rubber by the incorporation of materials that do not participate
significantly in the vulcanization process.

Release
agent (mold) (r) a substance applied to the inside surfaces
of a mold or added to a material to be molded, to facilitate removal
of the product from the mold.

Resilience
(r) the ratio of energy output to energy input in a rapid (or instantaneous)
full recovery of a deformed specimen.

Resilience,
impact (r) the ratio of output to input mechanical energy
in a rapid deformation and recovery cycle of a rubber specimen.

Resistivity,
volume the ratio of the electric potential gradient to the
current density when the gradient is parallel to the current in the
material.

Retarder
(r) a material used to reduce the tendency of a rubber compound
to vulcanize prematurely.

Reticle
(sc) a reproduction of the pattern to be imaged on the wafer (or mask)
by a step-and-repeat process. The actual size of the pattern on the
reticle is usually several times the final size of the pattern on
the wafer.

Reversion
(vulcanization) (r) deterioration of vulcanizate properties
that may occur when vulcanization time is extended beyond the optimum.

Rubber
(r) a material that is capable of recovering from large deformations
quickly and forcibly, and can be, or already is, modified to a state
in which it is essentially insoluble (but can swell) in a boiling
solvent such as benzene, methyl ethyl ketone or ethanol toluene azeotrope.

Rubber
hardness degree, international(IRHD) (r)
a measure of hardness, the magnitude of which is derived from the
depth of penetration of a specified indentor into a specimen under
specified conditions. The scale is so chosen that zero would represent
a material showing no measurable resistance to indentation, and 100
would represent a material showing no measurable indentation.

Runner
(r) the secondary feed channel for transferring material
under pressure from the inner end of the sprue to the cavity gate.

(sc)
This term is generally associated with the semiconductor industry.